This invention relates to homopolymerization of mono-1-olefin monomers, such as ethylene and propylene, and copolymerization of a mono-1-olefin monomers, such as ethylene and propylene, with at least one higher alpha-olefin comonomer.
It is well known that mono-1-olefins, such as ethylene and propylene, can be polymerized with catalyst systems employing transition metals such as titanium, vanadium, chromium, nickel and/or other metals, either unsupported or on a support such as alumina, silica, titania, and other refractory metals. Supported polymerization catalyst systems frequently are used with a cocatalyst, such as alkyl boron and/or alkyl aluminum compounds. Organometallic catalyst systems, i.e., Ziegler-Natta-type catalyst systems usually are unsupported and frequently are used with a cocatalyst, such as methylaluminoxane.
It is also well-known that, while no polymer production process is easy, slurry, or loop, polymerization processes are relatively much more commercially desirable than other polymerization processes. Furthermore, the type of polymerization process used can have an effect on the resultant polymer. For example, higher reactor temperatures can result in low catalyst activity and productivity, as well as a lower molecular weight polymer product. Higher reactor pressures also can decrease the amount of desirable branching in the resultant polymer.
Most polymer products made in slurry processes, especially those polymer products made using supported chromium catalyst systems, have a broader molecular weight distribution and, therefore, the polymer product is much easier to process into a final product. Polymers made by other processes, such as, for example, higher temperature and/or higher pressure solution processes, can produce polymers having a narrow molecular weight distribution; these polymers can be much more difficult to process into an article of manufacture.
Unfortunately, many homogeneous organometallic catalyst systems have low activity, high consumption of very costly cocatalysts, like methylaluminoxane (MAO), and can produce low molecular weight polymers with a narrow molecular weight distribution. Furthermore, even though MAO can be necessary to produce a polymer with desired characteristics, an excess of MAO can result in decreased catalyst system activity. Additionally, these types of homogeneous catalyst systems preferably are used only in solution or gas phase polymerization processes.
It is an object of this invention to provide novel catalyst systems useful for polymerization.
It is another object of this invention to provide catalyst systems which are relatively simple to make, have increased activity and increased productivity.
It is a further object of this invention to provide catalyst systems which have reduced cocatalyst consumption.
It is still another object of this invention to provide an improved polymerization process.
It is yet another object of this invention to provide homopolymers of mono-1-olefins and copolymers of at least two different mono-1-olefin(s) that can be processed easily, as indicated by increased branching and a broad molecular weight distribution.
It is still another object of this invention to provide homopolymers of mono-1-olefins and copolymers of at least two different mono-1-olefin(s) that have an increased molecular weight.
In accordance with this invention heterogeneous catalyst systems comprising diimine nickel complexes which further comprise additional ligands selected from the group consisting of xcex1-deprotonated-xcex2-diketones, xcex1-deprotonated-xcex2-ketoesters, halogens and mixtures thereof having a formula selected from the group consisting of Ni(NCRxe2x80x2C6R2H3)2(Y2C3Rxe2x80x32X)2 and Ni(NCRxe2x80x2C6R2H3)2(Y2C3Rxe2x80x32X)Z and methylaluminoxane are provided. Processes to make these catalyst systems also are provided.
In accordance with another embodiment of this invention, slurry polymerization processes comprising contacting ethylene, and optionally one or more higher alpha-olefins, in a reaction zone with heterogeneous catalyst systems comprising diimine nickel complexes which further comprise additional ligands selected from the group consisting of xcex1-deprotonated-xcex2-diketones, xcex1-deprotonated-xcex2-ketoesters, halogens and mixtures thereof in the presence of methylaluminoxane are provided.
In accordance with this invention heterogeneous catalyst systems consisting essentially of diimine nickel complexes which further comprise additional ligands selected from the group consisting of (xcex1-deprotonated-xcex2-diketones, xcex1-deprotonated-xcex2-ketoesters, halogens and mixtures thereof and methylaluminoxane are provided. Processes to make these catalyst systems also are provided.
In accordance with another embodiment of this invention, slurry polymerization processes consisting essentially of contacting ethylene, and optionally one or more higher alpha-olefins, in a reaction zone with heterogeneous catalyst systems comprising diimine nickel complexes which further comprise additional ligands selected from the group consisting of xcex1-deprotonated-xcex2-diketones, xcex1-deprotonated-xcex2-ketoesters, halogens and mixtures thereof in the presence of methylaluminoxane are provided.
In accordance with yet another embodiment of this invention, compositions comprising homopolymers of ethylene and copolymers of ethylene and one or more higher alpha-olefins which can be characterized as having high molecular weight, increased branching and a broad molecular weight distribution, are provided.